Collagen produced by cells cultured from patients with Marfan syndrome is more soluble than that made by cultures from normal individuals. The state of aggregation of Marfan collagen will be deduced from ion-exchange and molecular-sieve chromatography of extracts of radioactively labeled cultures. The state of crosslinking will be assessed by radioactively labeling the crosslinks and their precursors and then analyzing hydrolyzates by ion-exchange amino acid analysis. The proportions of different types of alpha chains will be determined by chromatography of labeled lathyritic collagen and differences in chromatographic behavior of peptide fragments of these chains will be sought. Any observed differences will be evaluated for use as a diagnostic aid. Similar observations will be made of collagen in dominantly-inherited osteogenesis imperfecta. We further hope to determine whether intracellular degradation of collagen can serve as a point of control of the amount secreted from a comparison of the ratio of amount degraded and amount secreted when lysosomal enzymes are increased by treatment with glycosaminoglycans.